Dilated cardiomyopathy (DCM) is a disease characterized by marked decreases in ventricular muscle contraction, resulting in dilatation of the heart, and the prognosis thereof is very poor as compared with hypertrophic cardiomyopathy. In Japan, the proportion of patients still alive five years after a diagnosis of DCM is said to be about 50%. While heart transplantation is desirable as a radical cure in the treatment of dilated cardiomyopathy, the number of donors is insufficient in comparison with the number of patients on the waiting-list, so that symptomatic therapies for cardiac failure are currently the core of the treatment. While cases where the heart function and prognosis were improved by the administration of an angiotensin converting enzyme (ACE) inhibitor or a β blocker have been reported, an effective therapeutic agent or treatment method is still desired.
According to a Matsui et al. report, the administration of a peptide resulting from addition of Cys to the second loop of β1 adrenoreceptor: His Trp Trp Arg Ala Glu Ser Asp Glu Ala Arg Arg Cys Tyr Asn Asp Pro Lys Cys Cys Asp Phe Val Thr Asn Arg Cys or a peptide resulting from addition of Cys to the second loop of M2 muscarine receptor: Val Arg Thr Val Glu Asp Gly Glu Cys Tyr Ile Gln Phe Phe Ser Asn Ala Ala Val Thr Phe Gly Thr Ala Ile Cys to rabbits resulted in appearance of an antibody to the peptide administered and dilated cardiomyopathy was found in the hearts of rabbits which died 9 months later; thus, it is suggested that each antibody acts as a cause of dilated cardiomyopathy (Non-Patent Document 1).
Ogino et al. report an adsorbent capable of adsorbing an anti-β1 adrenoreceptor antibody and/or an antibody against M2 muscarine receptor (Patent Document 1). Further, a peptide capable of binding to an autoantibody causing DCM has been reported (Patent Document 2).
However, the prior art peptides have a problem in that the time required for the reaction for immobilization thereof on a carrier is long. When they are long, the prior art peptides have a further problem from the viewpoint of yield in synthesis. Some amino acid residues in such peptides often induce a side reaction or reactions in peptide synthesis.
Patent Document 1: Japanese Kokai Publication 2001-286554
Patent Document 2: Japanese Kohyo Publication 2003-514772
Patent Document 3: Japanese Kohyo Publication 2002-504831
Non-Patent Document 1: Jpn Heart J., 1998, 39(3), 261-74